The NSABP is comprised of 177 active member institutions that are participating in treatment trials in the United States, Canada, Puerto Rico, and Australia. The Group has a more than 40-year history of conducting large-scale controlled clinical trials that have improved treatment for patients with breast or colorectal cancer and have provided a better understanding of tumor biology. This application requests continued funding for the NSABP Operations Center for the period February 1, 2000, through January 31, 2006. Major areas of emphasis in the NSABP include: evaluation of therapies in the adjuvant treatment of breast and bowel cancer; testing of new drugs, combinations of drugs, and biological agents in patients with advanced disease, with the primary goal of determining therapies that should be further evaluated in the adjuvant setting; identification of and validation of molecular markers of prognosis and response to therapy; reduction of the morbidity associated with breast cancer surgery through the evaluation of minimally invasive cancer surgery procedures; assessment of quality-of-life issues in selected studies, particularly equivalence trials of newer or less toxic therapies; analysis of data and publication of the results of NSABP studies in peer-reviewed medical journals; and enhancement of the participation of women and under-represented minorities in NSABP trials.